1. Field of the Invention.
This invention relates in general to alarm systems, and in particular to a portable arm system utilizing a light beam controlled radio transmitter and remote receivers to personally notify the individual users that a perimeter delineated by the light beam has been penetrated.
2. Description of Prior Art.
One of several potential uses of this invention relates to the safety of highway construction workers. Highway workers are often required by the nature of their work to be exposed to high speed traffic passing by very closely. All too frequently this exposure has resulted in tragedy when a confused, ill or drinking driver enters a construction area and strikes a worker. Often, death or injury could have been avoided had the worker received even momentary notice of the approaching hazard. Unfortunately, the constant sounds of traffic immediately adjacent to the work site makes listening for approaching hazards ineffective. The need for workers to focus their gaze on their work makes watching for approaching hazards impossible.
Heretofore several methods of providing protection to these employees have been utilized with various levels of sub-optimal effectiveness. One such effort involved the designation and assignment of an additional worker to each work site specifically to act as a designated lookout. Unfortunately, the use of a lookout was found to be ineffective for several reasons; (1) at the speed at which traffic is approaching a lookout's own reaction time acts to reduce the system's effectiveness, (2) after recognizing the hazard, there are inherent delays and difficulties in conveying a meaningful and effective warning, and finally, (3) difficulty in maintaining the requisite level of constant attention necessary on the part of the lookout. Therefore, the use of a lookout was abandoned as an ineffective solution to the problem.
Another previous effort aimed at mitigating this hazard involved the placement of an alarm system utilizing a pressure sensitive air hose, of the type previously common in gas stations, around the job site. A high volume siren type alarm was activated near the job site by an electronic device when the air hose was compressed by the weight of a vehicle crossing the line. This method had several critical drawbacks. To be effective, a warning system for this purpose must protect several hundred feet of perimeter. The weight and bulk of this much hose made deployment, occasional repositioning and storing the system very time consuming and physically demanding. But perhaps the most serious drawback associated with this prior art was related to the siren used to warn the workers. A very loud warning siren was placed in such proximity to the workers so as to be heard over the ambient noise of heavy construction equipment and passing traffic. The siren, so amplified, was of such a volume that it frequently startled the worker. This resulted in delayed and occasionally inappropriate reaction to the approaching hazard. Thus, the system itself occasionally created a hazardous condition. As a result of these problems, this approach was also abandoned.
Another commonly utilized method of providing for highway worker protection is to place heavy equipment within the closed roadway segment upstream from the work site. Large pieces of construction equipment are parked crosswise or otherwise blocking the travel lanes some distance from the workers. Unfortunately, this method too has several limitations. Frequently, enough heavy equipment to do the job and protect the work site at the same time is simply not available. Even when available, impacts into the equipment can result in injury to workers nearby. Also, the placement of such equipment is occasionally circumvented by errant drivers who occasionally steer around or otherwise avoid such obstacles. The effectiveness of this method would thus be greatly enhance when utilized in conjunction with this invention. The variety and complexity of these past efforts underscores the serious nature of the problem. Since 1970, 25 highways workers have been killed on the job in California alone. In 1982 the California Department of Transportation initiated a major public relations campaign entitled "Give'em a Brake". This program's primary aim is to emphasis the hazards inherent in this type of work to the motoring public. It's goal is to reduce the number of injuries and deaths of highway workers by asking the public to slow down near highway construction sites. However, injuries and deaths continue to occur. This fact indicates that improved methods to protect highway workers are still very much in demand.
Unfortunately, the problem will very likely get worse, not better. Urban freeways are becoming increasingly more congested. They are also becoming older and more often in need of repair. As traffic congestion becomes increasingly worse in urban areas, many construction projects are now being accomplished at night. Highway workers are at even greater risk during darkness. The lighting of the job site, with sufficient white light to do the work, detracts fom the effectiveness of even lighted traffic control devices. Driver confusion is more likely to occur during darkness. Perhaps even more problematic is the higher percentage of intoxicated drivers that historically plague our highways during these hours.
Each of the individual parts of this invention are commonly known electrical components. Some have been independently utilized for various highway safety and alarm related purposes. However, the individual components incorporated in the present invention have never been combined, offered for sale or utilized in any know application which incorporates a means to provide the type of protection made possible by this invention.
Nevertheless, several devices containing individual elements related to this invention will now be discussed. One such device incorporating a light beam activated detour sign is described in U.S. Pat. No. 3,896,414, Rulo, (1973). This device, entitled Roadway Detour System For Vehicles, utilizes a moveable light beam mounted on poles above the highway in conjunction with warnings signs activated by a light beam/photo cell mechanism. The sole purpose of this system is to sense the presence of over height vehicles and then to selectively activate warning signs and/or sirens to alert the driver of the over height vehicle in advance of the low obstruction ahead. While this device utilizes a light beam to control a detour sign and signaling system in a highway safety related area, it is otherwise totally unrelated to the present invention. The present invention utilizes a portable light beam and photo cell means to control a radio transmitter. An entirely different electronic purpose is therefore accomplished with a totally different highway safety objective.
Another related device is noted in U.S. Pat. No. 3,113,270, Bassett, (1959). This device, entitled Paging Alarm System, combines a small personal transistor radio type receiver, worn by a security guard or agent, with a series of panic or alarm activator buttons located at various points within a fixed protected area. A unique and specific tone is generated by the fixed radio transmitter dependent upon which one of the various panic or alarm activator buttons is utilized. Thus the location of the needed assistance can be recognized by a guard trained to recognize the specific tones. While a remote radio receiver is utilized in this fixed location alarm system, all other aspects of the present invention are distinctly dissimilar and designed to accomplish totally different objectives.
Finally, U.S. Pat. No. 2,099,868, Sing and Waunch (1935), describeds an Automatic Annunciator. This invention utilizes a light beam to detect the presence of an individual to initiate the playing of a phonographically recorded advertizement. Once again, while a light beam detection method is utilized, there is no further similarity with the present invention.